The present invention relates to a semiconductor integrated circuit device and to a mounting board. More particularly, it relates to a semiconductor integrated circuit device with improved reliability.
A mounting board for mounting thereon a semiconductor integrated circuit device having a plurality of power supply terminals and a plurality of signal terminals is used to supply a power supply voltage to the semiconductor integrated circuit device and perform signal input/output operations between the semiconductor integrated circuit device and the outside. Referring to the drawings, a conventional mounting board for mounting thereon a semiconductor integrated circuit device having a plurality of power supply terminals and a plurality of signal terminals will be described herein below.
FIG. 4 shows a structure of the conventional mounting board for mounting thereon the semiconductor integrated circuit device.
As shown in FIG. 4, a semiconductor integrated circuit device 2400 is mounted on a mounting board 2000 composed of a first-layer sub-board 2100 and a second-layer sub-board 2600. The first-layer sub-board 2100 is disposed on the second-layer sub-board 2600.
The semiconductor integrated circuit device 2400 comprises: signal terminal cells 2431 to 2446 formed on the semiconductor integrated circuit device; and power supply terminal cells 2451 to 2453, 2461 to 2463, 2471 to 2473, and 2481 to 2483 formed on the individual edge portion portions of the semiconductor integrated circuit device.
The signal terminal cells 2431 to 2446 are formed with respective signal terminal electrodes 2331 to 2346 for performing signal input/output operations between the semiconductor integrated circuit device 2400 and the outside.
The power supply terminal cells 2451 to 2453, 2461 to 2463, 2471 to 2473, and 2481 to 2483 are formed with respective power supply electrodes 2351 to 2353, 2361 to 2363, 2371 to 2373, and 2381 to 2383 for supplying the power supply voltage to the inside of the semiconductor integrated circuit device 2400.
The sub-board 2100 is provided with: input/output terminals 2101 to 2116; power supply terminals 2121 to 2123; signal lines 2201 to 2216; power supply lines 2251 to 2253; and power supply lines 2261 to 2263, 2271 to 2273, and 2281 to 2283. The input/output terminals 2101 to 2116 and the signal terminal electrodes 2331 to 2346 placed on the semiconductor integrated circuit device 2400 are connected to each other by the signal lines 2201 to 2216.
The power supply terminals 2121 to 2123 and the power supply electrodes 2351 to 2353 provided in the semiconductor integrated circuit device 2400 are connected to each other by the power supply lines 2251 to 2253. Between the power supply terminals 2121 to 2123 and the power supply electrodes 2351 to 2353, the power supply lines 2251 to 2253 are branched to be connected also to contact lines 2651 to 2653, respectively.
The electrodes 2361 to 2363, 2371 to 2373, and 2381 to 2383 on the semiconductor integrated circuit device 2400 are connected to contact lines 2661 to 2663, 2671 to 2673, and 2681 to 2683 by the power supply lines 2261 to 2263, 2271 to 2273, and 2281 to 2283, respectively.
The sub-board 2600 comprises power supply lines 2601 to 2603. The power supply line 2601 is connected to the power supply lines 2251, 2261, 2271, and 2281 on the sub-board 2100 via the contact lines 2651, 2661, 2671, and 2681, respectively.
Likewise, the power supply line 2602 is connected to the power supply lines 2252, 2262, 2272, and 2282 on the sub-board 2100 via the contact lines 2652, 2662, 2672, and 2682, respectively.
The power supply line 2603 is also connected to the power supply lines 2253, 2263, 2273, and 2283 on the sub-board 2100 via the contact lines 2653, 2663, 2673, and 2683, respectively.
A description will be given to the operation of the mounting board 2000 thus constructed.
If signals are inputted from the signal terminals 2101 to 2116, the signals are inputted to the electrodes 2331 to 2346 of the semiconductor integrated circuit device 2400 through the signal lines 2201 to 2216 formed on the sub-board 2100, respectively. Conversely, signals outputted from the semiconductor integrated circuit device 2400 are outputted from the electrodes 2331 to 2346 to the signal terminals 2101 to 2116 through the signal lines 2201 to 2216. In short, the signals are outputted by a route absolutely opposite to the route for the input signals.
A description will be given next to the supply of the power supply voltage.
The power supply voltage supplied from the power supply terminal 2121 is supplied to the electrode 2351 of the semiconductor integrated circuit device 2400 through the line 2251 formed on the sub-board 2100. Subsequently, the power supply voltage is supplied to the inside of the semiconductor integrated circuit device 2400 via the power supply terminal cell 2451. At the same time, the power supply voltage supplied from the power supply terminal 2121 is supplied to the power supply electrodes 2361, 2371, and 2381 successively through the power supply line 2251 formed on the sub-board 2100, the contact line 2651, the power supply line 2601 formed on the sub-board 2600, and the contact lines 2661, 2671, and 2681. Subsequently, the power supply voltage is supplied to the inside of the semiconductor integrated circuit device 2400 via the power supply terminal cells 2461, 2471, and 2481.
The power supply voltage supplied from the power supply terminal 2122 is supplied to the electrode 2352 of the semiconductor integrated circuit device 2400 through the line 2252 formed on the sub-board 2100. Subsequently, the power supply voltage is supplied to the inside of the semiconductor integrated circuit device 2400 via the power supply terminal cell 2452. At the same time, the power supply voltage supplied from the power supply terminal 2122 is supplied to the power supply electrodes 2362, 2372, and 2382 successively through the power supply line 2252 formed on the sub-board 2100, the contact line 2652, the power supply line 2602 formed on the sub-board 2600, and the contact lines 2662, 2672, and 2682. Subsequently, the power supply voltage is supplied to the inside of the semiconductor integrated circuit device 2400 via the power supply terminal cells 2462, 2472, and 2482.
The power supply voltage supplied from the power supply terminal 2123 is supplied to the electrode 2353 of the semiconductor integrated circuit device 2400 through the line 2253 formed on the sub-board 2100. Subsequently, the power supply voltage is supplied to the inside of the semiconductor integrated circuit device 2400 via the power supply terminal cell 2453. At the same time, the power supply voltage supplied from the power supply terminal 2123 is supplied to the power supply electrodes 2363, 2373, and 2383 successively through the power supply line 2253 formed on the sub-board 2100, the contact line 2653, the power supply line 2603 formed on the sub-board 2600, and the contact lines 2663, 2673, and 2683. Subsequently, the power supply voltage is supplied to the inside of the semiconductor integrated circuit device 2400 via the power supply terminal cells 2463, 2473, and 2483.
The foregoing conventional structure using the two-layer mounting board composed of the two sub-boards has the problem of increased fabrication cost for the mounting board.
To solve the problem, a method may be adopted which provides the semiconductor integrated circuit device 2400 with, e.g., only the power supply terminal cells 2451 to 2453 of the power supply terminals cells that have been provided conventionally on the four edge portions and supplies the power supply voltage to the entire semiconductor integrated circuit device 2400 from the inside thereof. If the power supply voltage is supplied to the entire semiconductor integrated circuit device 2400 from the inside thereof, however, there are cases where the semiconductor integrated circuit device 2400 does not operate normally due to a voltage drop or the like which prevents a sufficient current from being supplied to an end of the circuit. This leads to the conclusion that, since a current supplying ability which tends to be insufficient may cause the malfunctioning of the semiconductor integrated circuit device 2400, the foregoing method is impractical.